The information you see below is courtesy of VetSmart Pet Hospital & Health Center.

Hypothyroidism is caused when two small glands, located near the larynx (voice box), don't produce enough of the hormones T3 and T4. Since the body needs these thyroid glands to help turn food into energy, a slowdown in the body's metabolic rate is created if enough of these hormones aren't produced. It is now believed that hypothyroidism is usually an inherited condition. Often the condition may also be caused by illness, malnutrition or other causes.

Our Diagnosis:

In our diagnostic test at VetSmart for hypothyroidism, we start by measuring the level of T4 in the blood. This hormone can be more accurately measured since it is present at a concentration 25 times as high as the hormone T3. If it appears that your pet might have hypothyroidism, we can find out for certain by taking a small blood sample from your pet and analyzing it to find out how much T4 your pet has in its system.

In most cases, the T4 test is enough to tell us whether or not your pet is a victim of hypothyroidism. Occasionally, however, additional testing may be needed.

Effective Treatment:

There is a simple and effective treatment for hypothyroidism: A pet which has the disease must take tablets of replacement thyroid hormone every day - usually for the rest of its life. Most pets are given tablets twice daily. In some cases, dosage may be needed only once a day. If a reason develops for a change in treatement pattern, we will advise you after we examine your pet again. Please call us if you have any problem in getting your pet to take its medication. Being consistent in providing the tablets at the prescribed level is very important.


Behavior: You will probably notic an increase in your pet's physical and mental activity after about 10 days of medication. Most signs of hypothyroidism should be disappearing after two months.

Hair Growth: Your pet's hair will grow back in four to six months. Don't be alarmed if initially your pet begins to shed more hair than ever. Thyroid treatment causes new hairs to gorw which push out dead hairs that are left after hypothyroidism shuts down hair growth. Abundant shedding is actually a sign that the treatment is working!

Retesting Necessary:

In rare situations, the dosage prescribed may be too strong. If your pet starts to urinate frequently, drink a lot of water, become very restless, pants a great deal and loses considerable weight, please call us immediately. We will retest the T4 level and adjust the amount of thyroid replacement. Don't try to adjust the dosage yourself!

What to Look For:

Your pet's individual personality and overall physical condition may result in some changes which could be related to hypothyroidism. If your pet starts experiencing any of the following changes, it makes sense to have it tested as soon as possible.

Skin and Coat Changes:
Drying of skin and coat
Increased amount of shedding
Symmetrical hair loss
Less hair growth
Dandruff and itching
Skin turning black

Slowing of Metabolism:
Added weight, even with less food
Stiff movements or unsteady gait
Changes in heart beat
Trouble getting up

Frequent infections
Episodes of mild diarrhea
Abnormal bleeding

Decreased Signs of Fertility:
Lower sperm count in males
Females' heat cycles may not be intense, or may disappear completely, or be abnormal in some other way.

Sleeping more than usual
Dislike of going outside in cold weather
Slower mental activity
Decreased interest in playing in other regular activities

Follow Up Care

It's necessary to bring your pet to us on a planned basis, since the amount of T4 hormone must be adjusted to fit your pet's needs, and then kept at a steady level in the blood. A follow-up visit should take place two weeks to a month after starting the thyroid tablets or after the dosage has been adjusted. On the day of the visit, bring your pet early in the morning (by appointment) so we can draw a blood sample.

Please don't feed your pet for 12 hours before the test! Every hypothyroid patient should be retested every six months once on medication to make sure its requirements haven't changed.

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